Pulsed Water Injection for Engine Cylinder Balance
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Solution Overview
Problem
Existing water injection systems in internal combustion engines face issues with uneven water distribution among cylinders due to evaporation, mixing, and airflow maldistribution, leading to incomplete charge cooling and potential engine imbalances.
Innovation Solution
A method involving pulsing water injection into the engine intake manifold, synchronized with intake valve timing, and adjusted based on output from an intake manifold oxygen sensor and knock sensors to compensate for cylinder-to-cylinder variations, allowing for better distribution and balancing of water delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If water is injected into the engine intake manifold as a constant stream, then the water injection system is simple to operate, but the water distribution among cylinders becomes uneven due to evaporation, mixing, and airflow maldistribution
Solution Approach 1:
The patent applies periodic action by injecting water as multiple pulses synchronized with intake valve timing rather than as a constant stream. The controller delivers water in discrete pulses that coincide with each cylinder's intake valve opening event, ensuring periodic delivery that matches the engine's cyclic operation and improves distribution uniformity among cylinders
Solution Approach 2:
The patent applies segmentation by dividing the water injection into multiple discrete pulses, one for each cylinder's intake event, rather than injecting water continuously. This segmentation allows individual control of water delivery timing for each cylinder, addressing the maldistribution problem caused by constant stream injection
2Device complexity
If water is injected upstream of a group of cylinders, then the injection system requires fewer components, but water maldistribution occurs due to differences in runner location, size, and arrangement
Solution Approach 1:
The patent applies local quality by delivering water to each cylinder group with timing specific to that group's intake valve events. The controller adjusts the pulse timing for each injector based on the specific cylinder group's position and runner characteristics, providing localized optimization of water distribution while maintaining a relatively simple upstream injection system architecture
Solution Approach 2:
The patent applies preliminary action by synchronizing water injection pulses with the intake valve opening timing of each cylinder. The water is delivered just before or during the intake valve opening event, allowing the water to be properly entrained in the incoming air charge before the valve closes, compensating for variations in runner geometry
3Ease of manufacture
If the water injector angle or runner arrangement causes water to puddle, then the injection system is easier to install, but the cooling benefit is lost due to incomplete vaporization
Solution Approach 1:
The patent applies periodic action by injecting water in short, synchronized pulses rather than continuous streams. This pulsed delivery ensures water is introduced in discrete amounts that can properly atomize and vaporize during each intake event, preventing puddling while maintaining simple injector installation geometry
Solution Approach 2:
The patent applies continuity of useful action by ensuring water injection occurs continuously during the intake valve opening period of each cylinder. The pulsed injection timing is synchronized to maintain continuous cooling action across all cylinders throughout the engine cycle, preventing interruptions that would allow puddling to form
4Manufacturing precision
If pulsed water injection is synchronized with intake valve timing, then water distribution among cylinders is improved, but the control system becomes more complex
Solution Approach 1:
The patent applies feedback by using knock sensor signals and oxygen sensor data to monitor engine combustion and adjust water injection timing and quantity. The controller continuously receives feedback from these sensors and modifies the pulsed injection parameters to optimize water distribution and cooling effectiveness while compensating for cylinder-to-cylinder variations
Solution Approach 2:
The patent applies mechanics substitution by replacing complex mechanical timing mechanisms with electronic control. The controller uses electronic signals from the engine's existing sensor network (crank position, knock sensors, oxygen sensors) to electronically time the water injection pulses, eliminating the need for complex mechanical synchronization mechanisms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures more even water distribution, reducing knock tendencies and improving engine efficiency by optimizing air, fuel, and water delivery to each cylinder, thereby enhancing fuel economy and reducing emissions.
Implementation Method 1
When water is injected into the engine intake or cylinders, heat is transferred from the intake air and/or engine components to the water
Implementation Method 2
This heat transfer leads to evaporation, which results in cooling
Data Source
AI summary
Methods and systems are provided for learning a transport delay for individual cylinders that is associated with maldistribution of water among cylinders during a water injection event. Differences in knock intensity between individual cylinders, following a water injection, are used to identify water maldistribution. Differences in the amount and timing of an engine dilution effect following a manifold water injection are learned via an intake oxygen sensor and used to reduce cylinder-to-cylinder imbalance in water delivery.